Time switch



Aug. 2, 1932. J. J. JAKosKY ET AL.

TIME SWITCH 5 Sheets-Sheet l Filed Aug. 9. 1926 Aug, 2, 1932.

J. J. JAKSKY ET AL.

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Aug 2, 1932 J. J. JAKosKY ET AL TIME SWITCH Aug. 9'

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Patented Aug. 2, 1532 JOHN J. JAKOSKY, F LOS ANGELES, AND. ALFRED W. KNIGHT, 0F SOUTH PASADENA, CALIFORNIA, ASSIGNORS TO INTERNATIONAL )ERIECIPITATIONlv OOM-PANYg' OE'IOS ANISrIElLES,V CALIFORNIA, A CORPORATION OF CALIFORNIA TIME TSWITCH Application filed August 9, 1926. Serial'No. 128,090.'

This invention relates to -a device forfautomatic interruption of an electrical circuity at a definite time afterthe circuit is--closed or after the device is set in acertain position andA particularly to af device of this type Which is especially adapted for luse in connection with radio receiving sets,.electrical phonograph reproducers, or other `apparatus employing thermionic tubes.

rlhe main object ofthe invention is to providea time'switch which may be connected in the energizing circuit of a thermionic tube or tub-es and is adapted lto' cause such circuit to be automatically interrupted after the expiration of a' given timethus-preventing Waste-of electric energy due to failure to otherwise turn oif'the radio set or other. apparatus in which such tube is embodied. In the operation of radio `receiving sets and the like, the-operator customarily turns on an ordinary electrical switch of the push or pull or'other suitable type and it therefore becomes necessary When the operator is throughusing the set to again operate this switch so as to open the energizing circuit. It frequently occurs thatthe operator for some reason or other fails to so open the circuit and the tubes are thus. permitted to burn unintentionally for long periods, for example, over night, thus resulting in considerable Waste of elecT trical energy andrapid deterioration of the battery (or consumption of electrical power when anA` battery eliminator is used) and also deterioration of the tubes. The object of' this invention is to eliminate'these disadvantages.

A futher object of the invention is to provide a device for this purpose which may readily be installed in an ordinary radio receiving set and which is simple and positive in operation.

A furtherobjeet Lof the invention is to provide a device which may also be `operated to interrupt thecircuit at any time before the time of ,automatic cut-off. A further object of theinvention is to provide a circuit openingsivitch of such a type that at anytime before or after operation of the switch to automaticallyv interrupt the circuit, such switchmay be easilyreset or placed in opera'- tion so as to `continue the period during Which the circuit is maintained iny closedcondition While maintaining 1 an uninterrupted connection in circuit during such resetting-ofthe switch;

The device by WhichtheseobjeCtsarerac complished according 'to ourl invention Acomprises essentiallyy electricalv contact means adapted :to be lconnected in the `circuit toY be controlled, an operating member Inova-bile longitudinally in such-manner as to break the connection between said contactmeansfat acertain cut-off' 'position in its movement, means for moving said operating member fromsuch cutoff position, means. tending to returnl said operating member. to suchposition, andfmeans for-A controlling the rate at Which said loperatingmember is so returned. The device furthencomprisesin itsepreferred form additional'contaet means which lare also adapted to be connected in lthe circuit to be controlled"v and'v are so mounted 'that connection therebetween is interrupted by said operating'member when in another cLit-ofi'position, means for'moving saidloperating-member tol said 1 other cut-ofi? position, andV releasable retaining means for holding said operatingl member in such other position. The invention also comprises certainaddie tional features as hereinafter described.

The accompanying drawings illustrate embodiments of our invention and referring thereto Fig. l. is a longitudinal section lofone form of'switching device, the operating member beingshovvn at oneendv of its stroke. andthe circuit interrupted.'

v Fig. 2 is a. similar View with the operating member.4 in an Vintermediate position, at Which time the circuit is established.

Fig. 3 is a transversesection on line 3 3 in Fig. l.

Fig. 4 is atransverse section on linea-et in Fig. 1.

Fig. 5 is a transverse section on line 5-5 in Fig. l.`

Fig. 6 is a vievv similar to Fig. 5, the parts being shovvn in the position Which they occupy when the operating member is in the position shoWnin Fig.' 2.

Fig. 7 is a front view of the device.

Fig. 8 is a plan view, partly broken away.

Fig. 9 is a wiring diagram showing the manner of connection of our switching device in a radio receiving set.

Fig. 10 is a longitudinal section of a modified form of switching device.

Fig. 11 is a similar view, with the operating member shown in an intermediate position.

Fig. 12 is a transverse section on line 12-12 in Fig. 11.

Fig. 13 is a partial section on line 13-13 in Fig. 12.

Fig. 14 is a transverse section on line 14-14 in Fig. 10.

Fig. 15 is a plan view of another modificaj tion of the invention.

Fig. 16 is a longitudinal section of the device shown in Fig. 15.

Fig. 17 is a partial section of the same showing the manner of breaking connection between the contact means.

Fig. 18 is a partly sectional plan view of another modification of the invention taken approximately on line 18-18 in Fig. 20.

Fig. 19 is a longitudinal vertical section o the same.

Fig. 2O is a transverse section on line 20-20 in Fig. 19.

Fig. 21 is a partial vertical section ot' the same, showing the manner of breaking connection between the contact means.

The form of the invention shown in Figs. l to 7 inclusive comprises a cylindrical casing 1 having an end portion 2 provided with a tubular extension 3 forming a bearing opening within which is slidably mounted the tubular stem 4 of operating member 5, said operating member comprising in addition to such stem an outwardly extending flange 6 at the inner end thereof. At the other end of casing 1,an end member 7 is secured in any suitable manner, said end member having an inwardly projecting cylindrical portion 8. A suitable length of soft rubber tubing indicated at 10 is secured at its respective ends in any suitable manner to the flange portion 6 of operating member 5 and the inwardly projecting portion 8 of end member 7 as indicated respectively at 11 and 12. The means for so securing the rubber tubing at each orp its ends may, as shown in Fig. 3, comprise a clamping ring or strip 13 placed over the rubber tubing and provided at its ends with lip-turned portions 14 through which extends tightening bolt 15 provided with nut 16 so that said upturned portions may be drawn tightly together so as to hold the rubber tightly into a suitable annular recess or depression 17. A coiled or helical compression spring 2O extends within the tubular stem 4 and bears at one end against the head 21 of such stem and at the other end against the inner face or" end member 3. Said spring f is of such dimensions as to exert an outward force against the head 21 of said stem of the desired intensity for causing operation thereof as hereinafter described.

Suitable means are provided for controlling the rate at which the operating member is moved by said spring, such means coinprising for example a washer or gasket 24 of sponge rubber or other suitable porous resilient material adapted to control the flow of the working fluid, or in this case of air, through a small bleeder opening 25 into the fluid chamber 26 enclosed within rubber tubing 10 and the members 6 and 8. A washer 27 and nut 28 may be provided upon the threaded projection 29 which is secured to or formed integrally with member 8, for the purpose of adjusting the compression of the resilient porous member 24 and thereby controlling the rate of flow of air therethrough for the purpose hereinafter described. Means are'also provided for permitting outflow of air from chamber 26 when the operating member is pressed inwardly, such means comprising for example an outwardly opening check valve 42 of any suitable type mounted at the inner end of an air release passage 43 in an inwardly projecting stem 44 and projection 29.

Releasable retaining means are provided for holding the operating member in the position shown in Fig. 1, such means comprising for example, retaining springs 32 shaped as shown in Fig. 5 and mounted in any suitable manner within a central recess 33 in a rotatably mounted button or knob 31, which li fits over the outer end of the tubular sleeve 3. Said springs 32 are provided with inwardly bowed portions 34 adapted, when in the position shown in Fig. 5 to extend through openings 35 in tubular bearing portion 3 and engage in a retaining groove 36 in the stem 4 of operating member 5. The tubular bearing portion 3 is also provided with an annular groove 37, which is in line with the openings 35 and is of varying depth, being deepest adjacent said openings and gradually decreasing in depth away from the same in such manner as to practically disappear entirely or be substantially flush with the surface at points 38 mid-way between the openings 35. Such groove is further provided with two recesses 39 equally spaced from the respective openings 35, into which the bowed portions 34 are adapted to lit when knob 31 is turned as hereinafter described. A threaded retaining ring 45 may be screwed on the front end of tubular member 3 and adapted to engage a shoulder 46 on knob 31 so as to hold said knob against outward movement.

The device may be mounted on the panel 48 of the radio set or other apparatus in conne/ction with which the switch is to be used, by drilling a hole in such panel, as at 49, of the proper size to receive the sleeve member 3, and securing the casing to the panel by means of screws 50. It may be noted here that in mounting the device, the screws are put in place and tightened before mounting the knob 3l on sleeve 3. After tightening such screws the knobl is fitted over sleeve 3 and slid inwardly until the springs 32 engage in groove 37 after which the retaining ring 45 is screwed on. `When the knob is so secured in position it hides the heads of screws 50, thus giving a neat appearance. lf it is desired at any time to dismount the device, the retaining'- ring 45 may be unscrewed, and knob 3l turned to such position that the bowed portions 34 of springs 32 are moved out of groove 37 or to the shallowest portion thereof, as at points 38, when the knob may be readily withdrawn, again exposing screws 50. In order to indicate when the knob 3l is turned to effective retaining position and when it is out of-such position, a segmental plate 5l may be mounted on the panel above sleeve 3 and held in position by means of one of the screws 50, as indicated at 50', said plate being provided with suitable markings such as the fords Off and On7 as shown,

for indicating respectively when the knob is in the aforesaid positions. Knob 3l may be recessed as at 52 so as to make room for the head of screw 50 and permit turning of said knob.

Suitable Contact means are provided and are so disposed that connection therebetween is broken when operating member 5 is moved to certain positions. Such contact means may comprise two pairs of contact pins 54 and 55 secured to or mount-ed on cvlindrical casing 1 and interiorlv thereof, and two con tact springs 56 and 57 which are bent into semi-circular shape as shown in Fig. 4 and are also twisted in such manner that the middle portion of each spring lies substantially parallel to the casing so as to permit the same to be secured thereto as by means of bolts 58 and 53 respectively while the end 'portions thereof.` indicated at 59 and 60 respectively, lie in plane substantially perpendicular to the plane of the middle portion and are adapted to resiliently engage contact pins 54 and 55 respectively. Operating member 5 is provided with a pair of projecting arms or fingers 6l which may be secured'thereto in any suitable manner in diametrically opposite positions, said arms being provided with insulating sleeves or coverings 62 at their outer ends and being adapted to engage spring Contact portions 59 and 60 in the motion of said operating member so as to move said contact portions out of engagement with Contact pins 54 and 55 respectively. The bolts 58 and 53 may project through casing l, being thoroughly insulated therefrom as indicated at 64 and may be provided with nuts 65 so as to form terminals or binding posts for-connection of the wires of the circuit thereto as shown in Figs. 8 and 9.

Referring to `said Figs. 8 and 9 we have shown in the latter ligure a diagrammatic representation of a radio receiving setprovided with usual arrangements including thermionic tubes 66, 67, and 68, each provided with filament 69, grid and plate 7l. The energizing circuit for the filaments of said tubes comprises wires 72 and 73 connected' respectively to the two filament terminalsof all the thermionic tubes in parallel. The wire 72 is connected to the positive terminal of the A battery, while wire 73 is. shown as connected to t-he usual rheostat 74 whence` tery. `We have also shown the negative B battery terminal as connected to the negative A battery terminal and thence to the filaments of the several thermionic tubes and it will be Y seen that when the switch is connected in the manner shown, it serves to break connectlon in both the A. and B battery circuits.

The operation of this form of the invention is as follows:

Under normal conditions, when the tubes are de-energized thel stem 4 of operating member 5 is in the position indicated in Fig. l, and with knob 3l turned to the position shown in Fig. 5 the spring 32 engages groove 36 in said stem and holds the same in' this position. Also at this time the arrow 46 on knob 3l points to the word Off asV shown in Fig. 7. Vhen in this position arms 6l on the operating member engage, through insulating means 62, the end portions 59 of contact spring 56 and hold the same out of contact with Contact pins 54 so that theenergizing circuit is interrupted at this point.

lf it is desired to energize the tubes of the radio set or other apparatus in which such tubes are employed, the knob 3l is turned to l' the position indicated in Fig. 6, at which time the `arrow 46 on said knob points to the word On on the plate 5l. The bowed portions 34 of springs 32 engage in recesses 38 to hold the knob lightly in this position. Due to this removal of such bowed portions from the groove 36 in stem 4, such stem is released and is forced'slowly outwardly by spring-20- As the operating member moves outwardly chamber 26 increases in volume and a condition of partial suction is thus created therein until the excess pressure on the outside of the flanged portion 6 of the operating member is sufficient to balance the force exerted by spring 20. mitted to chamber 26 through the inlet opening 25, the rate of admission of such air being controlled by the degree of compression of the resilient porous washer24. Such conipression may be adjusted by tightening or Air is however slowlyl adloosening nut 28 to the desired point so as to give any desired rate of movement to the operating member 5. As soon as such operating member is started in motion the end portions 59 of contact spring 56 are released and make connection with contact pins thus completing the circuit as follows: F rom the negative A battery terminal, through wire 76 to contact terminal 58, through contact spring 56, pins 54, casing 1, pins. 55, Contact spring 57, terminal 53, and wire to the rheostat .and thence to the filaments of all the thermionic tubes, whence wire 72 leads to the positive A battery terminah It is obvious that the B battery circuit will also be completed at the same time.

The circuit will remain completed and the thermionic tubes remain energized uniformly, throughout the entire period of movement of operating member 5 from its initial position until it reaches a position at which the insu lating sleeves 62 of the arms 6l engage con; tact springs 60 so as to move them out or engagement with contact pins 55. When contact is thus broken, the circuit traced above is interrupted, so that if the operator should forget or fail to return the switch to its normally open position, the switch serves to automatically interrupt such circuit after the expiration of a moderate period, thus preventing any appreciable waste of electrical energy and deterioration of tubes and batteries. The length of time which it takes for said operating member to move between these two positions under the action of spring 2O may be controlled as above described by adjustment of nut 28 so that the therinionic tubes may be maintained in energized condition for any desired reasonable period. of time. For example in case of radio receiving sets it may be desirable to so adjust nut that the time of operation of the switch will be approximately one hour although if desired it is possible to vary such time between Wide limits for example from five minutes or less to two hours or more.

It will be seen also that as the operating member moves outwardly the stem 4 projects further and further beyond the front of knob 31 thus giving an indication when the operating member approaches position to engage contact spring 6() and if it is desired to continue the period of operation of the thermionic tubes beyond that for which the switch was initially set it is only necessary for the operator, either before the operating member so engages contact spring 6@ or at any other time during the operation of the time switch, to press the stem 4 inwardly to its initial position or to any other desired position. Vhen the operating member is thus pressed inwardly the air is permitted through such passage at any time. The electrical circuit is maintained in closed condid tion throughout such ie-setting of the switch. After being thus pressed inwardly the operating member will again start to move out at the same rate as before and the circuit will remain closed until it again reaches cut-off position. If desired, in order to assist in determining when to re-set the switch, visual indicating means such as scale 47 in Fig. 8 may be provided on stem 4 for indicating the position of the same. Stop means are provid-ed for the operating member, such means comprising for example a shoulder 63 on end member 2, against which the flange 6 is adapted to come to rest a suitable time after tlie arms 6l engage contact spring 57.

While the time switch is adapted to interrupt the circuit at a given time after being set in operation, it may be desirable in some cases to break the circuit before the expiration of that time and in such case it is only necessary to turn knob 3l back to its original position as shown in Figs. 5 and 7, at which time the arrow 46 points to the word OE and the bowed portions 34 of springs 32 engage openings 35 in sleeve 3. If stem 4 is then pressed inwardly to its original position the spring 32 will again engage groove 36 therein and hold it in this position, thus restoring the switching device to its normal open condition.

A modified form of the invention is shown in Figs. 10 to 14 inclusive. In this form of the invention a metallic cylindrical casing is provided which is closed at one end as at 81 and is connected at its other end to a head member 82 of suitable insulating material. Contact springs 83 and 84 are mounted at the respective ends of said casing, the spring 83 being insulated therefrom as indicated at 85 and the spring 84 being mounted on insulating head member 83. Said springs are adapted to resiliently engage shoulders 86 and 87 respectively on casing 8O so as to make contact therewith. rThe device may be mounted on the radio or other panel 48 as before, bv

means of screws 88 which extend through said panel and through or into insulating head member 82. A metallic sleeve or tubular bearing 89 may be threadedly mounted on head member 82 so as to project through a suitable opening 90 in the panel 48. Said sleeve is provided with an opening 91 and an annular groove 92 in line therewith for the purpose hereinafter described.

The operating member 5 may in this case comprise a stem 4, at the inner end of which is secured or formed a flange 94 on which is mount-ed a. leather washer 95 adapted to tightly engage the inside of casing 8O in such manner as to make a substantially air-tight fit therewith. Such washer may be clamped between iiange 94 and a retaining ring 96 by means of screws 97, and a spreading meinber 98 of lightspring brass or other suitable spreading membervmay advantageously be slotted in the 4usual manner of such devices as indicated in Fig. 10. An insulating member 99 isv also mounted on the operating member5 in; position to engage Contact springs 84 at the outer end of the stroke of such operating member as hereinafter described.

A stem member 101 may be provided which is threaded at its outer end as at 102 so as to receive nuts 103 which hold said stem member in position-and also serve for connectionV of one of the wires of the circuit thereto. Suitable means `.such as leather washers 104 are provided for making l'an air tight fit around said 4stem member. The inner endg of said stem` member serves to ,guide the compression spring which as before engages the end 21 of stem-4 and engages at its other end ashoulder 105 on stem member 101. Suitable means are also provided in this case for controlling the rate'of admission of air to chamber 26 betweenthe lea-ther washer 95 and the end member 81,-suchfmeans comprising, for eX- ample, screw `107, washer 108, and sponge rubber washer 109, which controls the iiow of air through inlet `opening 110.

The contact spring 84 may be mounted on insulatinghead member 82 by means of bolt 111, which isset in -a recessed portion of said head membemand nut 111'; and :a terminal bolt 112 may also beset in such recessed portion-and extend through the insulating head member 82 vand may extend through and be insulatedrom-ra flange 80 on casing 80 and provi-'ded at itsiouter end with nuts 113 for connection of the other wire ofthe circuit thereto. The bolts 111 and 112 may be connected by means of wire 114.

Suitable means are also provided in this case for releasably retaining the operating member in the positions-hewn in Fi g. 10, such means compri-sing for example a knob 115 provided with sa retaining spring 116 formed as shown in Fig. V14am-1d,provided with an inwardly projecting portion 117 adapted when in the :posi-tion shown in such figure to project throufghwthe opening 91 and engage in the'agroove 36 instem member 4. Retaining spring ,116 is falso bent back at one end as :at 118so 'as to `engage in groove 92 .and said Y spr-ingengages throughout Va considerable .portion of its length in an annular recess 119in 1knob 115 in rsu-ch manner that engagement fof spring 11'6'in groove 92 and in recess 119 servesito hold the knob on sleeve 89. The other 'end of spring 116 isbent over and engagesfafhole 120 in knob 115 so as to cau-se said spr-ing to be tunned with said knob.

`ln the operation yof this form vofthe linventionit will be seen `:thatfas vlong'as the operat 5 ing .member :is in any `intermediate position such as shown in F ig. 11, the electrical circuit is completed as follows: From terminal `102 through contact spring 83, shoulder 86, casing 80, shoulder 87, contact spring 84, bolt 111, wire 114, to terminal bolt 112. When, however, stem 4 is pushed inwardly to position shown in lfig. 10 with the knob 115 turned to the position shown in rig. 14, the inwardly projecting portion 117 of spring 116 engages in groove 56 and holds said stem in this position. it will be seen that at' this time the i'lange 94 of operating member A95 engages contact spring 93 to hold the same away from shoulder 86 so thatthe electrical circuit is interrupted this point. lf knob 115 is turned to Vany* other position the projecting portion 117 is raised out ot' opening 91 into the groove 92, thus releasing stem 4 `and permittlngthe operating member to be moved outwardly by means of spring 20. Suitable means may loe provided for indicating the 0n and Oil positions ofthe knob 115. Due to the air-tight ht of washer y98 `against casing. 80a condition of partial suction is as bei'ore created in chamber 26 andthe operating member is thus permitted to move outwardly only as fastas air is admitted through controlling means 109. When the operating member reaches the outer endV of its lstroke the insulating portion 99 thereon engages contact spring 84and moves the same `away-from its position oat engagement with shoulder 87 thus again breaking the connection at this point. It desired, in order to give a quick motion to the operating member at vthe end of its stroke and thus enable'it to more readily operate contact spring 84, a small opening 122 may be provided in casing 80 in such position that washer 98 passes said opening slightly before the operating member reaches the end of its stroke. lvVhen said washer passes said opening, air is suddenly admitted therethrough to chamber 26 :so that the remaining movement of the :operating member takes `place rapidly, thus ensuring'positive operation oaf spring 84,. Member 99 may be provided with a portion 100 which isadapb ed to engage stop means 122 on end member 82 and limit the outward movement of operating member 5 'so as .to prevent injury of Contact spring 84. The operating member may as before be pressed inwardly at any time, in order to continue the period of operation thereof, and may again be restored to normal position to open the `circuit at any time by turning the :knob back .to the position shown in Fig. 14 and again pressing stem 4 inwardly to its original position.

A simpler form vof the invention is `shown inFigs. 15 to117. The device shown in these figures comprises a cylindrical casing 125 closed at both ends as at'126 land 127 and hav- Ving a tubular sleeve ory bearing portion 128 at one end in 4which is sli'dably mounted the stem 129 of operating member 5. Said operating member comprises in addition to the stem 129, a cup-shaped member 130 mounted at thefinner end of said stem and carrying a leather washer 131 which is adapted to make --1 an air-tight fit with the inside of casing 125.

=rubber washer 134 may advantageously be placed under the nut 133 and the shoulder portion 132 may be provided with an airpassage 135 in such manner that tightening of nut 133 compresses the sponge rubber washer 134 to any desired degree and hence controls the rate of air flow through passage 135.

The sleeve 128 may be adapted to lit in a suitable hole or opening in the panel 48 as shown and may be threaded at its outer end to receive a retaining nut 137 which serves to mount the device on the panel. Compression spring 138 is provided inside casing 125 and engaging the inner end of operating member so as to tend to force the same toward the left in Fig. 16. The stem 129 may be provided at its outer end with a suitable handle or button 139 by means of which the stem may be drawn out to the desired position and said stem may be provided with scale means as indicated at 14() for indicating the position of said stem. Such scale means may be graduated in any desired manner for example as shown in Fig. it may advantageously be calibrated to read in terms of minutes and hours of operation so that the extent to which stem 129 is pulled out in any case will depend upon the desired time of operation.

At the inner end of casing 125 contact springs 142 and 143 are provided, such contact springs being mounted for example on end member 126 by means of terminal bolts 144 and nuts 145 and being completely insulated therefrom as indicated at 146. Said contact springs 'are provided respectively with contact points 147 and 148 which are adapted under the resilient action of said Contact springs to engage one another so as to close connection between the wires and 76, which may be connected respectively to contact members 142 and 143 in such manner that when the nut 133 is withdrawn from between the contact springs the electrical circuit is established. Therefore when it is desired to turn the switch on, the button 139 is pulled out until the desired period of operation is indicated on scale means 140, whereupon the electrical circuit is established. rlhe stem is then released and is slowly forced inwardly by spring 138. The resulting compression of air in chamber 26 between Washer erating member to return very slowly to its initial position. It will be understoodthat` in assembling the'device the nut'133 is so adtion, as in the-forms above described, if it isY desired to continue the periodv during which the circuit is completed beyond the time for which the switching device is initially set it is only necessary at any time before completion of the operation thereof to again dra-w the same outwardly to any desired position, and it will be seen that the electrical circuit is maintained closed during such resetting operation.

Another simple form of the invention is shown in Figs. 18 to 21 inclusive. It is believed that this form of the invention is so similar in general construction to the forms shown in Figs. 10 tov 14 inclusive as to require no detailed description. The operating member comprises as in such other form of the Vinvention a stem 4 and leather washer 95,

and compression spring 2O tends to force said stem outwardly. The iniow of air to chamber 26 is in this case controlled by a small needle valve 153 mounted at one end of the cylinder and communicating for example with the inside of hollow stem 154 which is open at its other end so as to provide communication with chamber 126. A sleeve 155 at the end of casing 8O is in this case inserted through an opening in the panel and a retaining nut 156 is screwed onto the end of said sleeve. f

The contact means in this form of the invention comprises a contact point 158 formed or mounted upon a laterally projecting portion 159 of the casing and another contact point 160 on contact spring 161 which is mounted on and insulated from said laterally extending portion 159 for example by means of terminal bolt 162. Another terminal bolt 166 is provided on the casing or the lateral extension 159 thereof for connection of the other wire of the circuit thereto. Contact spring 161 is provided at its end with an insulating portion 163 which is adapted to be engaged by shoulder or projection 164 on stem 4 when the same reaches a certain position in its stroke. A shoulder or stop member 165 may be provided at lthe end of casing 8O against which the shoulder 164 is adapted to engage shortly after engaging the insulating portion 163 on stem 161 and moving the same to open positionv to break connection between contact points 158 and 160 as shown in Fig. 21. The stem 4 is also shown in this case as prowith scale means 140 calibrated in In testimony whereof we have hereunto terms of time of operation. A band 167 ot subscribed our names this 31st day of July, distinguishing color, for example red or 1926.

white, may also be provided on stem 4, in such position as to come into View slightly before the contact is broken, thus furnishing a warning of this fact so that the switch may be reset if desired.

Under normal conditions when the circuit is not to be energized the operating member is in the position shown in Fig. 21 so that the electrical circuit is interrupted between contact points 158 and 160. l/Vhen it is desired to establish the circuit the stem member 4 is pressed inwardly until the desired time of operation is indicated on the scale means with which said stem is provided. Contact is thereby established between C011- tact members 158 and 160, thus completing the circuit and such circuit remains so completed until the operating member is forced by spring 20 into its original position, the rate of return of such operating member being so controlled by the flow of air through needle valve 153.

While we have particularly described the use of air as a working liuid for controlling the rate of operation of our switching device, it will be understood that any suitable fluid may be employed for this purpose. The device comprises, in any case, means delining a substantially luidstight leather washer sliding in a cylinder or a length of rubber tubing closed at both ends, an operating member having a portion forming a part of the wall of said chamber and movable so as to vary the volume of said chamber, means acting on the operating member to move the same, means for controlling iuid passage into or out of said chamber upon change in volume thereof, and contact means as above described controlled by said operating member.

lVe claim:

1. A time switch comprising, in combination with an electric circuit, contact means includ-ed in said circuit and operable to break the saine at either of two points, an operating member operable to irst cause operation of said contact means to close the circuit at one of said points while said circuit is closed at the other point and, at a predetermined time thereafter, to cause operation of said contact means to break the circuit at the other of said points, and manually releasable mea-ns for holding said operating member in a position of engagement with said contact means such as to cause the circuit to be held open at said one point.

2. A time switch as set forth in claim 1, said operating member being manually returnable to said position of engagement with said contact means at any time after release of said holding means.

JOHN J. JAKOSKY. ALFRED W. KNIGHT. 

